In this article, we report several potential problems found for the LS at low temperature, then develop a new recipe suitable for the ton-level TAO detector, based on the recipe for Daya Bay [1]} and for JUNO [2]}. Since we find that doping Gd or not has little impact to the LS behavior at low temperatures, we will not distinguish LS and GdLS in this paper unless necessary. In the following, first we will introduce the experimental setup to study the light transmission at low temperature. Then we study the light transmission of the LS solvent and LS with different concentrations of fluors. We cure the solubility decrease problem by adding co-solvent into the LS. Light yield of the new LS is also discussed.
